exif-mcp

Instructions

Implementation Reference

• src/tools/index.ts:154-170 (handler)

  Shared handler function that implements the core logic for the 'read-ihdr' tool. Loads image buffer, configures exifr options for IHDR via buildSegmentOptions('IHDR'), parses metadata, extracts 'ihdr' field, and returns it or an error response.

  async (args, extra) => {
    try {
      const { image } = args;
      const buf = await loadImage(image);
      const opts = buildSegmentOptions(segment);
      const meta = await exifr.parse(buf, opts);
      
      const segmentKey = segment.toLowerCase();
      if (!meta || !meta[segmentKey]) {
        return createErrorResponse(`No ${segment} metadata found in image`);
      }
      
      return createSuccessResponse(meta);
    } catch (error) {
      return createErrorResponse(`Error reading ${segment} data: ${error instanceof Error ? error.message : String(error)}`);
    }
  }

• src/tools/index.ts:54-60 (schema)

  Zod schema for ImageSource input parameter used by the 'read-ihdr' tool to validate image source (path, url, base64, or buffer).

  const ImageSourceSchema = z.object({
    kind: z.enum(['path', 'url', 'base64', 'buffer']),
    path: z.string().optional(),
    url: z.string().optional(),
    data: z.string().optional(),
    buffer: z.string().optional()
  });

• src/tools/index.ts:141-173 (registration)

  Registration of the 'read-ihdr' tool via the segmentTools array and forEach loop using server.tool, including name, description, schema, and handler.

  const segmentTools = [
    { name: 'read-icc', segment: 'ICC' },
    { name: 'read-iptc', segment: 'IPTC' },
    { name: 'read-jfif', segment: 'JFIF' },
    { name: 'read-ihdr', segment: 'IHDR' }
  ] as const;
  
  segmentTools.forEach(({ name, segment }) => {
    const segmentTool = server.tool(name,
      `Read ${segment} metadata from an image`,
      {
        image: ImageSourceSchema
      },
      async (args, extra) => {
        try {
          const { image } = args;
          const buf = await loadImage(image);
          const opts = buildSegmentOptions(segment);
          const meta = await exifr.parse(buf, opts);
          
          const segmentKey = segment.toLowerCase();
          if (!meta || !meta[segmentKey]) {
            return createErrorResponse(`No ${segment} metadata found in image`);
          }
          
          return createSuccessResponse(meta);
        } catch (error) {
          return createErrorResponse(`Error reading ${segment} data: ${error instanceof Error ? error.message : String(error)}`);
        }
      }
    );
    tools[name] = segmentTool;
  });

• src/tools/segments.ts:114-128 (helper)

  Helper function buildSegmentOptions that creates exifr options specifically for IHDR by setting options.ihdr = true when segment='IHDR', used in the read-ihdr handler.

  export function buildSegmentOptions(segment: 'ICC' | 'IPTC' | 'JFIF' | 'IHDR'): ExifrOptions {
    const options: ExifrOptions = {
      tiff: false,
      xmp: false,
      icc: false,
      iptc: false,
      jfif: false,
      ihdr: false,
    };
    
    const key = segment.toLowerCase() as 'icc' | 'iptc' | 'jfif' | 'ihdr';
    options[key] = true;
    
    return options;
  }

• src/tools/index.ts:18-27 (helper)

  Helper function to standardize successful MCP tool responses, used by read-ihdr handler.

  function createSuccessResponse(data: any) {
    return {
      content: [
        {
          type: "text" as const,
          text: typeof data === 'string' ? data : JSON.stringify(data, null, 2)
        }
      ]
    };
  }